#include<bits/stdc++.h>
using namespace std;using ll=long long;const ll inf=1e17;
struct S
{
	vector<int>ec;int rot,cnt=0,mx=0;
	vector<vector<int>>es;
	int spr(int x,int lst)
	{
		int cc=0;for(auto k:es[x])if(k!=lst)cc+=spr(k,x);
		mx=max(mx,cc);if(!cc){cnt++;return 1;}return 0;
	}
	void solve()
	{
		int n;cin>>n;es.resize(n+1),ec.resize(n+1,0);
		for(int i=1,u,v;i<n;i++)cin>>u>>v,es[u].push_back(v),es[v].push_back(u),ec[u]++,ec[v]++;
		for(int i=1,mx=-1;i<=n;i++)if(ec[i]>mx)mx=ec[i],rot=i;if(ec[rot]==n-1) { cout<<"-1\n";return; }
		spr(rot,0);cout<<max(mx,(cnt+1)/2)<<'\n';
	}
};
int main()
{
	//freopen("3.in","r",stdin);
	//cout<<fixed<<setprecision(12);
	ios::sync_with_stdio(0);cin.tie(0);
	int t=1;cin>>t;
	//clock_t a=clock();
	while(t--){S SS;SS.solve();}
	//cout<<"Time:"<<double(clock()-a)<<'\n';
}